Researchers at the Naval Research
Laboratory (NRL) have demonstrated the first real-time hyperspectral
target detection system flown aboard a Predator Unmanned Air
Vehicle (UAV). The recently completed demonstration is called
WAR HORSE (Wide Area Reconnaissance Hyperspectral Overhead Real-Time
Surveillance Experiment). During the demonstration, data from
a nadir-looking visible hyperspectral sensor were analyzed by
an on-board real-time processor. When a target was detected,
a high-resolution image was collected from a bore-sighted panchromatic
visible sensor. A three-band false-color waterfall display of
the hyperspectral data with overlaid target cues, along with
the corresponding high resolution image chips, were transmitted
to a ground station in real time via a digital RS-170 data
link.
The NRL-developed hyperspectral
sensor records reflected light in many narrow contiguous bands
in the visible/near infrared wavelength region of the electromagnetic
spectrum. The push-broom sensor consists of a grating spectrometer
and a 1024x1024 custom charge-coupled device (CCD) camera. The
sensor operates at a frame rate of 40 Hz and provides 1024 cross-track
spatial pixels and 64 wavelength bands (450-900 nm). The NRL
panchromatic imaging sensor also operates in the visible wavelength
region. It consists of a CCD line scanner and a large format
lens ( 300 mm). This sensor operates at a frame rate of 240
Hz and provides high-resolution imagery via 6000 cross-track
spatial pixels. The systems signal processor and interface computer
was developed by Space Computer Corporation and NRL and consists
of two DSPs (digital signal processors) and a Pentium II processor.
The DSPs perform all calibration and run a subspace RX anomaly
detection algorithm in real time. A custom board encodes digital
data to a video compatible analog output with forward error correction.
By means of a RS-170 video data-link, data are transmitted to
the ground in real time. A high-frame-rate video frame grabber
and custom demodulation software decode the transmitted data,
which consists of a false-color waterfall display, target cue
information and corresponding high-resolution image chips.
The WAR HORSE system was flown
on a Navy Predator UAV (from the Naval Postgraduate School) over
the Camp Roberts training facility in California. Typical flight
parameters for the Predator were an altitude of 10,000 feet and
an airspeed of 70 knots. This provided a hyperspectral imager
ground sampling dimension of approximately one meter and a
high-resolution
line scanner ground sampling dimension of approximately six
inches.
This exercise was performed as
part of the Optical Sciences Division's DARKHORSE Project, which
is part of NRL's ONR-funded 6.2 Base Program. Over the past
six years, this project has been developing algorithms to detect
and classify ground targets in clutter and camouflage, based
on their spectral, spatial and temporal signatures. In addition,
this project first demonstrated autonomous, real-time detection
and cueing from an airplane, first with a hyperspectral visible
sensor then a hyperspectral long wave infrared sensor. The technology
demonstrated has evident applicability to UAV and Uninhabited
Combat Air Vehicle (UCAV) programs, as well as the HISTAR system
on the EP-3 and the SHARP system on the F-18.
The U.S. Naval Research Laboratory is the Navy's full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 85 years and continues to meet the complex technological challenges of today's world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.
Comment policy: We hope to receive submissions from all viewpoints, but we ask that all participants agree to the Department of Defense Social Media User Agreement. All comments are reviewed before being posted.